1. Field of the Invention
The present invention relates to a hydrocyclone separation system and, more particularly, to such a system which includes at least two hydrocyclone separation devices tangentially staged for improved separation efficiency.
2. Setting of the Invention
Vortex separators or hydrocyclones, such as the type shown in U.S. Pat. No. 3,306,461, have been utilized in the past for the separation treatment of liquid suspensions or multidensity fluids, as well as fluid/solid mixtures. In such hydrocyclones, liquid is fed tangentially into an upper cylindrical portion and, as the liquid flows through a conical lower portion, the liquid is accelerated. Centrifugal force draws the more dense components to the outer portion of the rotating column of liquid. The more dense components of the liquid are discharged through an opening in the conical lower portion, and the separated less dense components are passed upwardly through a centrally located opening.
It is advantageous to introduce the incoming liquid so that the more dense components therein have a relatively short distance to travel, because the efficiency of the hydrocyclone is a function of the ability to direct the more dense components against the inner surface of the hydrocyclone while the less dense components move towards the center and out through the central upper opening.
Further, it has been found that hydrocyclones used alone are not as efficient as a plurality of smaller hydrocyclones arranged in series. Various hydrocyclone systems have been used in the past that included several separators coupled in series. By using at least two hydrocyclones in series, the liquid processed by the second hydrocyclone has been stripped of larger solids which might plug the inlet openings of the second hydrocyclone, which is usually smaller in diameter. This is particularly important within the drilling industry, since inlet and outlet plugging are major problems in operating the preferable small diameter hydrocyclones.
One system commonly utilized is shown in FIG. 1, wherein a liquid/solids mixture is tangentially introduced into a first hydrocyclone. The less dense components of the first hydrocyclone are then introduced tangentially into a second, usually smaller, hydrocyclone. The less dense components exit the first hydrocyclone as a rotating upwardly traveling fluid stream. Within this stream, the higher density components are already at the outer periphery of the stream, i.e., the higher density components are already partially separated before they are introduced into the second hydrocyclone. In prior art series of hydrocyclones, the rotating upwardly traveling stream is passed into a conduit before entering the second vortex separator. Within this conduit, the stream's rotation is stopped or greatly diminished, thereby causing the semi-separated higher density components to be remixed prior to being reseparated within the second hydrocyclone.
The inventor hereof knows of no arrangement of hydrocyclones where the less dense components of a first hydrocyclone are introduced into a second hydrocyclone to maintain the same direction of rotation so that the higher density components are not remixed, thus increasing the efficiency of the series of hydrocyclones.